1. Field of the Invention
This invention relates to liquid filter systems and, more particularly, to a filter system having a replaceable filter unit that can be hermetically sealed before assembly and disassembly thereof to facilitate handling and disposal of the filter unit.
2. Background Art
Capsule-type filter systems, employing a replaceable filter unit, are used in a wide range of environments. For example, it is known to use these systems for filtering pressurized oil used in hydraulic circuits and/or for purposes of lubrication.
Typically, filter systems used for oil in hydraulic equipment have a main body which is placed in line on an oil delivery conduit to divert the oil to and through a filter medium. Many of these filter systems use a replaceable cartridge/filter unit that fits in a receptacle defined by a housing that is removably connected to the main body. The filter units typically have concentric, cylindrical, porous cores, with filtering medium disposed within the annular space between the cores. The filtering medium is folded to define pleats which account for an enlarged filtering surface area. The filtering medium is captively held between axially spaced plates. After a designated period of time, the housing is separated from the main body to expose the filter unit which is removed and replaced with a new filter unit.
During the replacement procedure, the spent filter unit drips oil and contaminants that adhere principally to the filter medium, thereby exposing the user handling the filter unit to the oil and contaminants. Further, cleanup of the area surrounding the filter system may be necessary. Still further, disposal of the spent filter unit is messy and inconvenient. Commonly after a change of filter unit takes place the used filter unit is placed in another receptacle to facilitate its transportation and may ultimately be disposed of with the transporting receptacle.
Further, once the filter unit is removed, any residual pressure in the conduit, into which the filter system is integrated, causes oil, that would be otherwise held captive by the housing for the filter unit, to discharge. It is often necessary to close the valves upstream and downstream of the filter system prior to removing the filter unit to avoid this condition, particularly at altitudes where atmospheric pressure is significantly reduced.